Davit control mechanism



DeC- 23, 1952 D. E. DoDGsoN DAVIT CONTROL MECHANISM 5 Sheets-Sheet l Filed May 31, 1949 INVENTOR. 04u/ E. 0 650A/ BY Dec. 23, 1952 D. E. DoDGsoN 2,622,251

DAVIT CONTROL MECHANISM Filed May 51, 1949 3 Sheets-Sheet 2 A INVENToR.

Dec. 23, 1952 D. E. DODGSON DAVIT CONTROL MECHANISM 3 Sheets-Sheet 3 Filed May 3l, 1949 Rm w N0 m m l @m/ w M Patented Dec. 23, 1,952l

UNITED vSTATES PATENT OFFICE Application May 31, v1949, serial No. 96,326

' 2 Claims.

This invention relates to davits and more particularly to hydraulically operated mechanism for selectively moving a pair of davit arms supporting a lifeboat or the like yto inboard and outboard position.

Strict lawsV have been enacted requiring passenger and merchant vessels to be equipped with specified numbers of lifeboats, depending on the size of the vessel and the number of passengers and crew members carried. Such lifeboatsare generally carried inboard under davits or checks, and must be stowed in such a manner that they can be launched in the shortest possible time and under unfavorable conditions of vessel: list and trim.V

In general, there are three types of davits in present use for moving a boat from its inboard or'jstowedposition to an outboard or launching position. The rst of these types 'is the gravi'tyjdavit wherein the lifeboat is carriedon two cradles, mounted on rollers, which move over two parallel tracks at right angles to the side o'lffthevessel. In operation, a lever controlling a jbrake'is raised which permits the lifeboat and Athe entire'assembly to roll down the tracks byfgravity, stopping withrthe lifeboat suspended overv the side of the vessel and at the level of the embarkation deck.l This type of davit has certainv advantages, but the tracks `require-'a `large amountof room inboard of the vessel, and cons'clueitly'acertain proportion of overhead' deck space ifs wasted. Furthermore,4 the'cost of this system isvery high and its use is therefore restrictedf by economic considerations. Another type's fthev radial or round bardavits inrwhich tnefdavits are rotated aft 'umu the bow. of the lifeboatclears the forward davit; The forward davit isthen' turned out's'o that the bow swings outyfd the same Vprocedure is then followed with the'z'afte'r davit. The-third type is commonly eferredtoas quadrantal davits in which the davits arepivoted at their lower ends and are rotated loutboard at right angles to the vessels side'by means of a crank operating a worm gear. This latter type of davit has been extensively used, particularly on merchant vessels, but has the4 primary disadvantage in that six or more men are required to operate the cranks to move the-boat tof'its outboard position. This disadvantage'is similarly present in the radial'or round bar davit. Furthermore, a great deal of physical effort is required on the part of the crew to place the boat in lposition for launching, anda considerable amount of time is requiredfor -the operation.

` #It is therefore an object ofmy invention to provide operating mechanism for boat supporting davits which will cause the davits to move the boat to the outboard or launching position in a minimum period of time. v

A further object of the present invention is to provide a boat supporting davit which may be easily operated by a single individuali.,

Anotherobject of my invention is to provide a davit operating mechanism which maybe located on the deck of a vessel soA as to take up a minimum amount of deck space.

A still further object of my invention is to provide a davit operating mechanism of the type described which may be installed at only a fraction of the cost of certain existing mechanisms.

Still another object of the invention is to provide automatic means for moving a davit from inboard to `outboard position, such means being capable of installation on a new vessel or usedv in combination with the presently operated hand-cranked types of davits.

' The' invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however,v that variations in the showing made by the said drawings and description may be adapted withinthe scope of the invention as set forth in the claims.

Referring to the drawings:

' Figure 1 is aside elevational view of a pair o boat supporting davits and operating mechanism embodying my invention.

Figure 2 is a detailed sectional view Aof the valve system used in my hydraulic operating mechanism. l.

Figure 3 is an end elevational view of the boat supporting davit taken along the plane indicated by line 3-3 Of-Figure 1, the full lines indicating the normal inboard position of the davit, and the dotted lines the outboard or boat launching position. Y

Figure 4 is an end elevational view similar to Figure 3 illustrating the application of my invention to a crank-operated quadrantal type of Figure 5 is a detailed plan View of the operatingmechanism used in the embodiment illustrated in Figure 4.

Figure 6 is an enlarged elevational view of a portion of the operating mechanism disclosed in Figure 4 showing engagement of the clutch.

Figure '7 is a sectional view of a portion of the operating mechanism taken on plane l-l of Figure As previously stated, there are numerous types of boat supporting davits in current use. but in general, such davits have undesirable features such as expensive installation, excessive bulli, or diiculty in operation. Many improvements have been suggested for eliminating one or more of these dimculties, but none of these improvements have met with too favorable a reaction in the trade. While certain of these improvements have obviated one of the undesirable features, it has generally been at the expense of one of the other features. In an attempt to improve upon existing davit installations and to develop a new type of davit for future installations, the present inven tion was made. v

Referring to the drawings, and with particular' reference to Figures l and 2, the boat supporting davits are positioned inboard of the vessel side and are arranged for pivotal'inovement outboard of the vessel whereby a lifeboat may be moved from a stowed to a Alaunching position. A lifeboat l l is here shown as being -supported on suitable conventional falls l2 and releasinggea-r i3 permitting the release of the falls from the boat either before the boat is waterborneior immediately thereafter. Thefalls are connected to. and supported from the distal lli of a pair of davits I5 in any suitable manner but preferably by means of a block and tackle ll'hanging from a hook i3 at the end ifi of the davit, the lower end i9 of the davit being pivotally connected to the vessel by means of a pin 2l extending through suitable apertures in the davits and in channel shaped support members' 23.

Means are provided for moving the davits around the pivot pin from their vertical or stowed position to their outboard or launching position indicated by the `dash-dot lines in Figure 3. Although numerous power methods could be utilized for moving the davits, it is imperative that the boats also be capable of being launched by manual operation, maritime law requiring such a safeguard in case of'power failure on board the vessel. Therefore, I have illustrated a preferred method of davit operation which includes the use of a two-way hydraulic cylinder operable either by hand or power actuated pumps, although it will be clear to those skilled. in the art that other hand or power actuated means could be used.

Referring again to Figures l and a pair of'A- l frames 22are provided at each davit, being interconnected at their upper ends by a preferably crlindrical shaft 23 journaled or otherwise affixed to the frames. The frames are here shown as be ing supported on a member secured to the decl;- ing 2S of the vessel in any suitable manner, but desir-ably tied in-to the deck stringers 21 or the ribs 29 to lend structural stability to the entire operating mechanism. 'interposed between the shaft 23 and the davit it is a hydraulic inder 29 provided at one end the 1eof with a pair of ears 3l with apertures therein for receiving the shaft 23 and effecting a pivotal connection between the shaft and cylinder. The cylinder is also provided with a piston secured to an opel1r` rod 33 extending through one end of the cyli ier and pivotally connected to a bracket extension 3 of the davit with a pivot pin In this manner. the cylinder is pivotally supported at its rea-rr rd end, and by extending or retraeting the piston and its associated rod, it is apparent that the davit may be selectively moved to its inboard and ou*- board position.

To effect movement of the piston Within cylinder 29, hydraulic means are provided, and such means are capable of either mechanical or manual operation. In general, a motor driven pump and a. hand-operated pump are arranged in parallel, whereby either pump may be actuated to force fiuid into cylinder 29 and effect movement of the piston 32 therein. As shown in the drawing, a motor 3l is operatively connected to a hydraulic pump 33 which is rin ow communication with cylinders 29 through a conduit 38. A T fitting 4l is also provided whereby each of the cylinders will be in communication with the pump 38 through the respective conduits 39 and 4U. However, in case of an electrical power failure on board the vessel, I also provide a hand pump 42 with a suitable operating handle 43. This hand pump may be of conventional design, and as hand pumps, motors and hydraulic pumps are well known to those skilled in the art, and as they constitute no part of the present invention, no further description will be-made herein. Y. The handA pump l2-fis in communication with cylinders 29 through a conduit i4-and to prevent back pressure from building up in the Ypump-.when the electrically operated pump isfunctioning, a ball-check valve d5 is provided in conduit. Conduits 39 and i4 are connectedY by a T 46- and enter-a common conduit 41 leading to the cylind-er. A two-way valve generally indicated by the numeral lil is utilized to effect movement of the piston 32 -in either direction in cylinder 29 whereby the davits may be selectively moved to inboard and outboard positions. Separate conduits i9 and 5I are respectively connected to the front and rear portions of cylinders 29 and conduit 52 is provided -fordraining fluid from `one side of the piston to a suitable-reservoir located in the pump housings when the piston is actuated toward saidl side.v As best seen in lFigure 3 the valve 48 has a rotary plug member 53-operable by handle 55 which has therein va pair of lseparate ducts 54 and 5S respectively arranged to connect adjacent pairs of the four peripherally disposed, equidistantly spaced portsl with which the rotary plug member isprovided. -These parts are arranged toregister and communicate with similarly arranged ports in the valve body. The ports of the valve body'are connected to conduits 41, 49, 5l and 52 respectively. Withthe plug 53 positioned as shown in Figure 3, fluid entering-conduit 4'! from either pump will be caused toA flow through duct 59'to `conduit 5| thereby forcingthe fluid under pressure to the rear end of cylinder 29'and urging the piston therein to its forward position, while at the same time conduit 49 which is connected to the frontend of cylinderf29 will receive fluid being forced out of the cylinder by forward movement ofthe piston and therfiuid will pass through duct 54 into conduit-52 and thence'into selected reservoirs associated with pumps 38 and |532. By rotating plugmember 53 ninety degrees, the duct 54 will register With conduits 41 and i9 and the duct 55 will registeren/ith conduits 5I and 52. Under the latter condition, fluid under pressure will be forced against'theforward endof the piston and fluid behind the pistonin the cylinder will be drained. 'T0-rotate plug member 53, a handle 51 is provided, and-by means of suitable linkage 59 anda pivot pin 59, fore and aft movement of the handle will eiect rotation of the plug member.V

Suitable conduits are provided so that simultaneous reception of uid in the same side of each cylinder is accomplished. As the cylinder is pivotally connected, it is necessary toprovide ilexible portions El. onY the conduits connected therewithf-Its understood of fcurise, that thfex tire conduit system may be made' of iiexibletubing.-

It will beapparentfromth' Vvforegoing that a simple means cf selectively moving davits tol their inboard and loutboard positions has been accomplished which is'capable of being operated either mechanically or manually by a single individual in a fraction of the time heretofore required for the operation.

4In Figures 4"'through 8 is illustrated the application of hydraulic means in combination with the conventional type quadrantal davit which is generally provided with a plurality of teeth 66 formed along an arcuate path, the teeth being arranged to engage matching teeth 61 in the davit frame 68. To rock or pivot the davit around the frame, a hand crank 69 is provided which is secured to a threaded shaft 1I supported by suitable bearings in the frame. A threaded sleeve member 12 mounted on the davit is engaged on the shaft, and it is thus seen that by rotating the hand crank, member 12 will be caused to move inboard or outboard depending on the direction of rotation and effect the lowering or raising of the davit. While this system is satisfactory in certain aspects, a great deal of physical force is required to move the davits when a boat is supported thereon, and I have therefore provided means whereby the davits may be selectively pivoted by mechanical and hydraulic means as Well as by use of the hand crank.

In carrying out the invention, it will be generally necessary to extend shaft 1I inboard of the frame 68 to provide a shaft extension 13 to which the hand crank is connected. Mounted on theextension 13 adjacent the frame 99 is a spur gear 14 in operative engagement with a gear 16 on a shaft 11 which is horizontally spaced from extension 13 and supported on one end by a bearing 18 mounted in an eXtension 19 of frame 68. Means are provided to effect rotation of gear 16 which in turn will cause rotation of gear 14 and shaft 1l and pivoting of the davit. Such means include a pump 8| driven by an electric motor 82, the pump being operatively connected to a hydraulic cylinder 83 through a valve similar to that shown i'n Figure 2 of the drawing. Cylinder 83 is the same as cylinder 29 and is provided with a piston and conduits 84 and 86 leading to the valve and to the cylinder of the other davit. The piston rod extension 81 is provided with teeth 88 to form a vertically extending rack, the teeth B8 engaging the teeth of a pinion gear 69 splined to a shaft 9| mounted in suitable bearings provided in a support frame 92. Thus, by raising or lowering the piston in the cylinder, the vertically moving rack will cause rotation of pinion 89 and shaft 9|. To impart this rotation to shaft 11, a novel clutch arrangement is provided, and as here shown comprises matching dogs 93 and 94 mounted on adjacent ends of shafts 11 and 9| respectively. An alignment pin 96 is also provided to support one end of shaft 11 and to maintain the dogs in axial alignment. In order to provide selective separation or engagement of the clutch dogs, the shaft 9| may be moved axially in the frame 92 and such movement may be accomplished in several ways, but as here shown, comprises the use of a lever arm 91 pivoted at a center portion by means of a pivot pin 98 extending through a pair of ears 99 formed on frame 92 and pivoted at its distal end to a member ll secured to the end of shaft 9|. By pullingV on the handle 91, the shaft l9|Vwill`fbe caused to withdraw throughfframe 92 and disengage the clutch dogs, and conversely, by pushing on the handle, clutch engagement is effected. It is to be noted that pinion 89 is somewhat wider than the rack teeth 88 whereby interengagement of the gears are not affected by the limited degree of axialmovement of shaft 9| which is required to disengage the clutch dogs.

- -If it is desired to operate the davit mechanism by hand, lever 91 is pushed in disengaging the clutch dogs 93 and 94 and permitting manual operation of the hand crank 69. Or if it is desired to operate the mechanism mechanically, by pulling the lever 91, the clutch dogs will engage, and by aligning the proper ports of the valve mechanism with the appropriate conduits of cylinders 83, the piston will travel in the cylinder effecting vertical travel of the rack and subsequent rotation of pinion 89, gears 16 and 14, and shaft 1I which will impart the pivotal movement to the davit. In this manner, one person can easily bring a lifeboat to inboard or outboard position in a minimum period of time.

I claim:

l. Boat launching apparatus having a support platform, a substantially vertical davit having its lower end pivotally mounted on said platform, a substantially horizontal manually rotatable first shaft, means engageable with said davit and said rst shaft for effecting pivotal movement of said davit upon rotation of said first shaft, a cylinder mounted on said platform and having a piston therein, means for selectively introducing fluid under pressure to said cylinder on either side of said piston, a piston rod having a plurality of teeth thereon, a second shaft having a pinion mounted thereon in engagement With said piston rod teeth, means for imparting rotation from said second shaft to said flrst shaft, and clutch means interposed between said shafts for selectively placing said shafts in and out of operative engagement.

2. Boat launching apparatus having a support platform and including a plurality of horizontally disposed teeth, a substantially vertical davit having a plurality of teeth formed along an arcuate path and engageable with said platform teeth, a susbtantially horizontal threaded first shaft longitudinally secured in said platform, means including an internally threaded sleeve secured to said davit and mounted on said shaft for imparting pivotal movement to said davit on rotation of the shaft, a gear mounted on said first shaft, a cylinder mounted on said platform and having a piston therein, means for selectively introducing fluid under pressure to said cylinder on either side of said piston, a piston rod attached to said piston and having a plurality of vertically spaced teeth thereon, a second shaft, means including a gear engageable with said rod teeth for effecting rotation of said second shaft on axial movement of said piston rod, a third shaft, means including a gear on said third shaft engaged with said first mentioned gear for interconnecting said first and third shafts for imparting simultaneous rotation therebetween, and clutch means interposed between said second and third shafts whereby said first shaft may be selectively placed in and out of operative engagement with said second shaft.

DAVID E. DODGSON.

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